Photographic diffusion transfer process



3,068,098 Patented Dec. 11, 1962 States Patent @fifice This invention relates to photographic processes for producing direct positive images and to materials for use therein.

In photography, most of the layers in which photographic images are found are themselves originally lightsensitive. However, not all photographic layers used for forming images are light-sensitive and the present invention concerns a class of non-light-sensitive layers, namely, those containing development nuclei for silver salts or substances forming development nuclei at a suitable stage in the photographic process or precipitants for silver salts by double decomposition. Such non-light-sensitive layers are used to form positive silver or silver salt images therein by reaction between the substances in-the layers and dissolved silver salts diffusing thereinto from the unexposed areas of contiguous silver halide emulsion layer. which has been exposed image-wise and which has been or is being developed to a negative image.

One drawback sometimes encountered in processes of this type is that the positive image produced is of a brownish or other non-acceptablecolor.

The present invention provides a sheet material comprising a non-light-sensitive photographic layer containing a silver precipitating agent such as development nuclei, or a substance capable of forming development nuclei with dissolved silver salts or a precipitant for silver salt, and al containing a compound of one of the following general formulas:

wherein R R and R may each be hydrogen or a lower alkyl group, R may be a lower alkyl group, 'or R and R may together represent the non-metallic atoms necessary to complete a heterocyclic ring, R is a lower aIkyl group, and X may be 0 or S.

R and R may be, for example, hydrogen, methyl or ethyl; when R is hydrogen, R may be cyclohexyl; R and R together may complete a piperidyl or morpholinyl ring; and R may be a lower alkyl group such as methyl or isopropyl.

The invention includes the process of preparing a direct positive image which comprises exposing a photographic silver halide emulsion layer to an object or image, developing a negative image in the exposed layer, and during or after development, transferring silver halide by diffusion from the unexposed areas of the emulsion layer to a non-light-sensitive image-receiving layer containing a silver precipitating agent such as development nuclei or a substance capable of formingdevelopment nuclei presence of a silver halide solvent and a compound of one of the above general formulas.

By in effective contact, we mean that dissolved silver salts can diffuse from the emulsion layer to the nonlight-sensitive layer. There may be an intermediate layer present between the two aforesaid layers which does not hinder the silver salt dilfusion, and the two layers may or may not be coated on the same support.

We have foundthat the presence of one of the compounds of the present invention has the effect of producing a blacker positive image than would otherwise be produced.

In the process of the invention, the said compound may be present in the receiving layer or in the solution empoyed for effecting development in the emulsion layer.

An alkaline solution is used to efiect development of the exposed layer and the developing agent may be present in either the emulsion layer or in the alkaline solution or both. A mixture of developing agents may be used,

if desired. Y

The silver halide solvent may be present in the developing solution or the receiving layer and is preferably sodium thiosulphate. It is preferable to employ an antifoggant to prevent the formation of fog in the exposed emulsion layer and this may be present in either the emulsion layer or in the alkaline solution used to effect development. Any of the well-known nitrogen-containing organic antifoggants may be used and it has been found that benztriazoles are very suitable.

The comphnds of the invention are preferably employed in the following concentrations: from 8 to 80 mgs./sq. meter, when incorporated in the receiving layer;

' or from 0.05 to 1.0 gram/liter, when incorporated in the developing solution.

A suitable non-light-sensitive image-receiving layer for use in the present invention comprises a gelatin layer containing a substance constituting development nuclei such as colloidal silver or silver sulphide) or a substance forming development nuclei with dissolved silver salts (such as zinc sulphide), and also containing one of the compounds of the invention.

Such a layer may be coated on a paper support and contacted in the presence of a silver halide solvent with an washing in warm Water.

The following examples illustrate the present invention:

EXAMPLE 1 A high contrast silver chloride emulsion containing the following constituents is coated on a paper support at the mentioned coating rate:

Grams/ sq. m.

Silver chloride 1.4 Diphenyl iodonium-S-rnethyl benztriazole 0.063 Hydroquinone 0.28 Gelatin 5.6

I The resulting emulsion layer is exposed to a subject 3 such as a document and treated with the following developer:

Grams Sodium sulphite (anh.) 75 Hydroquinone v 18 Sodium hydroxide 1.5 1-phenyl 3-pyraz'olidone 0.5

Water to 1 liter.

During or after development, the exposed emulsion layer containing developing agent is squeegeed for about 20 seconds into contact with an image-receiving sheet comprising a light weight paper support bearing a nucleated layer as follows:

" Grams/ sq. m.

Gelatin 6.1. Sodium thiosulphate (anln) 1.4 Titanium dioxide 0.63

Colloidal silver sulphide 0.0027 3-cyclohexylaminomethyl 5-methyl- 2-thiooxazolidine 0.036

After separating the layer and the. sheet, a positive imageof a neutral black color. was, obtained on the receiving sheet.

Similar results were obtained when employing, instead of 3-cyclohexylaminomethyl-5-methyl-2-thiooxazolidine,

the following compounds in the specified amounts:

Grams/ sq. m. 3,4-morpholinylmethyl-S-rnethyl-Z- thiooxazolidine 0.036 3,4-piperidylmethyl-S-methyl-Z- thiooxazolidine 0.036 Isopropyldi-(5-methyl-2-thiooxazolidin- 3 -ylmethyl) amine 0.021 Methyldi-(5-methyl-2-thiooxazolidin- 3 -y lmethyl)amine 0.021 Methyldi-(Z-thiothiazolidin-S- ylmethyl)amine 0.021

EXAMPLE 2 The procedure of Example 1 was repeated. with the exception that 3,4-morpholinylmethyl-5-methyl-2-thiooxazolidine was employed in the developer (0.05 gram/ liter) and there was no toning agent in the receiving sheet. A positive image of a neutral-black color was obtained in the receiving sheet. 1

Similar results were obtained when employing, instead of 3,4-morpholinylmethyl-5-methyl-2-thiooxazolidine, the following compounds in the specified amounts:

Grams/liter Isopropyldi-(5-methyl-2-thiooxazolidin 3-ylmethyl)amine 0.075 Methyldi-(5-rnethyl-2-thiooxazolidin- 3 -ylmethyl)a mine 0.075 Methyldi-(2-thiothiazolidin-3- ylmethyl)amine 0.075

The compounds referred to in the above examples, may be prepared as described in the following preparations.

Preparation 1 CHs-CHO CH, =s

N GHQ-H2 as N V 1 0 CHrCflz 3,4'-morph01lnylmethyl-5-methyl-Z-thiooxazolidine 39 grams of -methyloxazoline-2-thiol were heated slowly in 37% formalin (27 ccs.). At 50 C. a light brown oil had formed. Ethanol (2O ccs.) was added and the temperature was lowered to 25 C. A solution of morpholine (29 grams) in ethanol ccs.) was then added while cooling under running water. The mixture from benzeneflight petroleum (60-80 C.) as colorless needles M.P.. 90 C.

Preparation 3 S-cyclohexyiaminomethyl-5 methyI-Z-thiooxazolidlne This was made according to the method described in U..S. 2 ,343,566.

30 Preparation 4 CHr-CH-O O---O-CHs 1. t=s se B N JHi-N (5H2 C'IH Ca \CH; 40 Iso-propyldi- 5 -methy1-2-thiooxazolidin-3-y1methyl) amine,

5-methyloxazoline-2-thiol (131 grams) was heated slowly in 37% formalin (85 ccs.). At C. a light brown oil had formed. Ethanol (20 ccs.) was added and the temperature was lowered to 25 C. A solution r of iso-propylamine (32.5 grams) in ethanol (10 cos.) was then added while cooling under running water. The mixture was stirred vigorously and a white crystalline solid separated. It was twice recrystallized from alcohol as colorless crystals M.P. 140 C. yield 141 grams.

50 Preparation 5 CHr-CH- O O--CCH3 Hz 0:8 8:0 CH1 H2-N C HI Methyldi- (5-methyl-2-thiooxazolidin-3-ylmethyl amine This was prepared as. in.the above example, using 5- 6O methyloxazoline -2-thiol (65.5 grams) and 37% formalin (42.5 ccs.); ethanol (10 ccs.) was added at 50 C. At 25 C.. 33% alcoholic methylarnine solution (51.6 ccs.) was added with cooling. The mixture was stirredrapidly and the resulting oil set aside to chill to give a solid grams) which was recrystallized from ethanol (6 ccs./ grams) as colorless needles M.P. 83 C. I

Preparation (IJH:S 2 7o (Egg/0:8 S=C CH2 7 Methyldi'(2-thiothiazolidin-S-ylmethyl)amine .comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and a compound having a general formula of the class consisting of and (3112 N-$H2 it,

wherein R R and R are selected from the class consisting of hydrogen and lower alkyl groups, R; and R are selected from the class consisting of lower alkyl groups, and R and R are selected from the class consisting of non-metallic atoms necessary to complete a heterocyclic ring of the class consisting of morpholinyl and piperidyl and X is selected from the class consisting of oxygen and sulfur atoms.

2. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and a compound of the class consisting of 3-cyclohexylaminomethyl-S-methyl-Z-thiooxazolidine, 3,4'-morpholinylmethyl-5-methyl-2-thiooxazolidine, 3,4'-piperidyl- 9 methyl-S-methyl-Z-thiooxazolidine, isopropyldi-(S-methyl- 2-thiooxazolidin-3 -ylmethyl amine, methyldi- S-metnyl-Z- thiooxazolidin-3-ylmethyl)amine and methyldi-(Z-thiothiazolidin-3-ylmethyl) amine.

3. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and 3-cyclohexylaminomethyl-5-methyl-2-thiooxazolidine.

4. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and 3,4-morpholinylmethyl-5'-methyl-Z-thiooxazolidine.

5. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and 3,4-piperidylmethyl-S-methyl-2-thiooxazolidine.

6. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and isopropyldi- S-methyl-2-thiooxazolidin-3-ylmethyl amine.

7. A process for preparing a photographic image which comprises exposing a photographic silver halide emulsion layer to a subject, developing the emulsion layer, then transferring the silver halide by diffusion from the undeveloped areas of the emulsion layer to an image-receiving layer containing a silver precipitating agent, the transfer being effected in contiguity with a silver halide solvent and methyldi-(5-methyl-2-thiooxazolidin-3-methyl)amine.

8. The process of claim 1 wherein the designated compound is present in the developer solution during the transfer step.

9. The process of claim 1 wherein the designated compound is present in the image-receiving layer during the transfer step.

References Cited in the file of this patent UNITED STATES PATENTS 2,699,393 Weyde Jan. 11, 1955 FOREIGN PATENTS 783,793 Great Britain Oct. 2, 1957 

1. A PROCESS FOR PREPARING A PHOTOGRAPHIC IMAGE WHICH COMPRISES EXPOSING A PHOTOGRAPHIC SILVER HALIDE EMULSION LAYER TO A SUBJECT, DEVELOPING THE EMULSION LAYER, THEN TRANSFERRING THE SILVER HALIDE BY DIFFUSION FROM THE UNDEVELOPED AREAS OF THE EMULSION LAYER TO AN IMAGE-RECEIVING LAYER CONTAINING A SILVER PRECIPITATING AGENT, THE TRANSFER BEING EFFECTED IN CONTIGUITY WITH A SILVER HALIDE SOLVENT AND A COMPOUND HAVING A GENERAL FORMULA OF THE CLASS CONSISTING OF 